Nanozymes have received extensive attention in the fields of sensing and detection, medical therapy, industry, and agriculture thanks to the combination of the catalytic properties of natural enzymes and the physicochemical properties of nanomaterials, coupled with superior stability and ease of preparation. Despite the promise of nanozymes, conventional nanozymes are constrained by their oversized size and low catalytic capacity in sophisticated practical application environments. single-atom nanozymes (SAzymes) were characterized as nanozymes with high catalytic efficiency by uniformly distributed single atoms as catalysis sites, thus effectively addressing the defects of conventional nanozymes. This paper reviews the activity improvement scheme and catalytic mechanism of SAzymes and highlights the latest research progress of SAzymes in the fields of biomedical sensing and therapy. Eventually, the challenges and future directions of SAzymes are discussed in this paper.

Nanozymes, as an emerging representative of nanocatalytic technology, have recently been widely used in the treatment of tumors. However, considering the limitation of the tumor microenvironment (TME) on the catalytic activity of nanozymes, the efficacy of cancer therapy appears to be more resistant. In this paper, we have synthesized PVP/MnO2‐Ti3C2 composites by combining MXene and MnO2 nanozymes and modifying them with polyvinylpyrrolidone (PVP). MnO2 brings dual enzymatic activities to the composites. It can alleviate tumor hypoxia by O2 production and kill tumor cells by producing highly toxic ⋅OH. In addition, glutathione (GSH) overexpressed is also depleted. MXene brings PTT, which not only can ablate tumors using local high temperature under the irradiation of NIR laser but also further improves the efficacy of ROS. Thus, this study provides evidence for the enhanced efficacy of PTT in combination with CDT for tumors.